This invention relates to a two-cycle engine fuel composition and method for using same. More particularly, this invention is directed to a two-cycle engine fuel composition containing a two-cycle engine fuel together with a lubricant component and, as a fuel additive, a hydrocarbyl polyoxyalkylene aminoalcohol.
In general, the use of spark-ignited two-cycle (also referred to as two-stroke cycle or 2-stroke) internal combustion engines has steadily increased over the years. These engines have typically been employed in power lawn mowers and other power-operated garden equipment, power chain saws, pumps, electrical generators, marine outboard engines, snowmobiles, motorcycles and mopeds.
Several problems exist with the use of two-cycle engines. Among the problems that are associated with the two-stroke cycle engines are, for example, piston ring sticking, piston scuffing, rusting, lubrication related failure of connecting rod and main bearings and the accumulation of deposits such as carbon and varnish deposits on various parts of the engine, e.g., the combustion chamber and on the fuel intake and exhaust system of the engine. The existence of these problems can affect the performance of the engine. For example, piston ring sticking can lead to failure of the sealing function of piston rings which typically results in loss of cylinder compression. This is particularly damaging in two-stroke cycle engines because many of these engines depend on suction to draw the new fuel charge into the exhausted cylinder. Thus, ring sticking can lead to deterioration of engine performance and unnecessary consumption of fuel and/or lubricant.
The presence of deposits in the combustion chamber can often result in the following problems to the engine: (1) reduction in the operating efficiency of the engine; (2) inhibition in the heat transfer between the combustion chamber and the engine cooling system; and (3) reduction in the volume of the combustion zone which can cause a higher than design compression ratio in the engine. A knocking engine can also result from deposits forming and accumulating in the combustion chamber. A prolonged period of a knocking engine can result in stress fatigue and wear in engine components such as, for example, pistons, connecting rods and bearings.
In view of the foregoing problems associated with, for example, the formation and accumulation of deposits in the combustion chamber and fuel intake and exhaust systems of a two-cycle internal combustion engine, efforts have been made to develop a fuel composition by mixing a fuel and lubricant component together with a third component lubricant additive. Illustrative of these third component lubricant additives are those disclosed in U.S. Pat. Nos. 5,498,353 and 5,888,948.
In accordance with the present invention, a two-cycle engine fuel composition is provided which comprises (a) a major amount of a two-cycle engine fuel; (b) a lubricant component; and, (c) a two-cycle engine fuel combustion deposit-inhibiting amount of at least one hydrocarbyl polyoxyalkylene aminoalcohol of the general formula 
wherein R1 is an alkyl, an alicyclic or an alkylalicyclic radical having from about 4 to about 30 carbon atoms or an alkylaryl where the alkyl group is from about 4 to about 30 carbon atoms; x is an integer from 0 to about 5, y is an integer from 1 to about 49, z is an integer from 1 to about 49 and the sum of x+y+z is equal to 3 to about 50; R2 and R3 each is different and is an alkyl group of from 1 to 4 carbon atoms and each oxyalkylene radical can be any combination of repeating oxyalkylene units to form random or block copolymers; R4 is the same as R2 or R3; R5 is hydrogen or 
where R7 is hydrogen or an alkyl group of from 1 to 5 carbon atoms; and R6 is hydrogen or an alkyl group of from 1 to 5 carbon atoms.
It shall be understood herein that mixed oxyalkylene groups constituting the polyoxyalkylene chain in the foregoing general formula may contain random or block sequencing.
Further in accordance with this invention, a method for inhibiting the deposition of fuel combustion deposits in a two-cycle engine is provided which comprises operating the two-cycle engine employing as the fuel therefore a two-cycle engine fuel composition which comprises (a) a major amount of a two-cycle engine fuel; (b) a lubricant component; and, (c) a two-cycle engine fuel combustion deposit-inhibiting amount of at least one hydrocarbyl polyoxyalkylene aminoalcohol of the general formula 
wherein R1, R2, R3, R4, R5, R6, x, y and z have the aforestated meanings.
The two-cycle engine fuel composition of this invention will inhibit the deposition of fuel combustion deposits in the combustion chamber and intake valves and exhaust system of a two-cycle engine. In general, the fuel composition will contain (a) a major amount of a two-cycle engine fuel; (b) a lubricant component; and, (c) an effective two-cycle engine fuel combustion deposit-inhibiting amount of at least one hydrocarbyl polyoxyalkylene aminoalcohol.
Suitable two-cycle engine fuels for use herein, i.e., gasoline base stocks, ordinarily contain a mixture of hydrocarbons boiling in the gasoline boiling range of from about 90xc2x0 F. to about 370xc2x0 F. This fuel can consist of straight or branched chain paraffins, cycloparaffins, olefins, aromatic hydrocarbons, or mixtures thereof. The fuel can be derived from among others, straight run naphtha, polymer gasoline, natural gasoline, or from catalytically cracked or thermally cracked hydrocarbons and catalytically reformed stock. Generally, the composition and octane level of the fuel are not critical and any conventional two-cycle engine fuel can be employed herein.
The lubricant component employed herein can be any lubricating oil used in a two-cycle engine. Suitable lubricating oils for use herein can be any natural oil, synthetic oil or mixtures thereof. Useful natural oils include mineral lubricating oils such as, for example, liquid petroleum oils, solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types, oils derived from coal or shale and the like.
Useful synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, etc.; poly(1-hexenes), poly(1-octenes), poly(1-decenes), and the like and mixtures thereof; alkylbenzenes such as dodecylbenzene, tetrade cylbenzenes, dinonylbenzenes, di(2-ethylhexyl)-benzenes, and the like; polyphenyls such as biphenyls, terphenyls, alkylated polyphenyls, and the like; alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivative, analogs and homologs thereof and the like.
Other useful synthetic lubricating oils include oils made by polymerizing olefins of less than 5 carbon atoms such as ethylene, propylene, butylenes, isobutene, pentene, and mixtures thereof. Methods of preparing such polymer oils are well known to those skilled in the art.
Further useful synthetic oils include alkylene oxide polymers, i.e., homopolymers, interpolymers, and derivatives thereof where the terminal hydroxyl groups have been modified by esterification or etherification. These oils are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and amyl ethers of these polyoxyalkylene polymers (e.g., methyl poly propylene glycol ether having an average molecular weight of 1,000, diphenyl ether of polyethylene glycol having a molecular weight of 500-1000, diethyl ether of polypropylene glycol having a molecular weight of 1,000-1,500, etc.) or mono- and polycarboxylic esters thereof such as, for example, the acetic esters, mixed C3-C8 fatty acid esters, or the C13Oxo acid diester of tetraethylene glycol.
Yet further useful synthetic lubricating oils include the esters of dicarboxylic acids e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic aicd, linoleic acid dimer, malonic acids, alkyl malonic acids, alkenyl malonic acids, etc., with a variety of alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc. Specific examples of these esters include dibutyl adipate, de(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.
Esters useful as synthetic oils also include those made from monocarboxylic acids having from about 5 to about 12 carbon atoms and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, and the like.
Other useful silicon-based oils include poly-alkyl-, polyaryl-, or polyaryloxy-siloxane oils and silicate oils. Examples of these include tetraethyl silicate, tetra-isopropyl silicate, tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-hexyl)silicate, tetra-(p-tert-butylphenyl)silicate, hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes, poly(methylphenyl)siloxanes, poly(methylphenyl)siloxanes, and the like. Other synthetic lubricating oils include liquid esters of phosphorous containing acids, e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decane phosphionic acid, etc., polymeric tetrahydrofurans and the like.
Unrefined, refined and rerefined oils, either natural, synthetic or mixtures of two or more of any of these of the type disclosed hereinabove can be used in the fuel composition of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many of these purification techniques are known to those of skill in the art such as solvent extractions, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.
In general, the lubricant component of this invention will have a lubricating viscosity (in cSt at 40xc2x0 C.) ranging from about 10 cSt to about 60 cSt and preferably from about 30 cSt to about 40 cSt. Typically, the lubricant component will be added to the two-cycle engine fuel composition of this invention in an amount ranging from about 1 weight percent to about 6 weight percent, preferably from about 1.5 weight percent to about 2.5 weight percent and more preferably from about 1.7 weight percent to about 2.2 weight percent, based on the weight of the fuel composition.
The hydrocarbyl polyoxalkylene aminoalcohol possesses the general formula 
wherein x is an integer from 0 to about 5, y is an integer from 1 to about 49 preferably from about 5, y is an integer from 1 to about 49 preferably from about 5 to about 40 and more preferably from about 5 to about 10, z is an integer from 1 to about 49, preferably from about 5 to about 40 and more preferably from about 5 to about 10 and the sum of x+y+z is equal to 3 to about 50; R1 is an alkyl, an alicyclic or an alkylalicyclic radical having from about 4 to about 30 carbon atoms or an alkylaryl where the alkyl group is from about 4 to about 30 carbon atoms, including by way of illustration, unsubstituted straight or branched aliphatic, cycloaliphatic and aromatic groups and cycloaliphatic and aromatic groups substituted with one or more straight or branched aliphatic, cycloaliphatic and/or aromatic groups. Thus, for example, R1 can be represented by the general formula 
wherein R8 is a hydrocarbyl group of from about 4 to about 30 carbon atoms including, by way of example, a monovalent aliphatic radical having from about 6 to about 24 carbon atoms, preferably from about 8 to about 20 carbon atoms and more preferably from about 9 to about 18 carbon atoms. R2 and R3 each is different and is an alkyl group of from 1 to 4 carbon atoms and each oxyalkylene radical can be any combination of repeating oxyalkylene units to form random or block copolymers with the random copolymers being preferred for use herein; R4 is the same as R2 or R3; R5 is hydrogen or 
where R7 is hydrogen or an alkyl group of from 1 to 5 carbon atoms; and R6 is hydrogen or an alkyl group of from 1 to 5 carbon atoms. The preferred hydrocarbyl polyoxyalkylene aminoalcohol for use herein as a fuel additive is 4-n-nonylphenoxypoly(propylene oxide-co-butylene oxide)-(2-N-butylalcohol)amine)-1-butyl ether and is represented by the following formula 
wherein the average value of y is from about 7 to about 8, the average value of z is about half that of y, i.e., from about 3.5 to about 4, with the ratio of y to z being from about 1 to about 3 and preferably from about 1.5 to about 2, R4 is xe2x80x94CH3 or xe2x80x94CH2CH3 and the sequencing of the propylene oxide/butylene oxide groups are random.
The foregoing hydrocarbyl polyoxyalkylene aminoalcohol can be obtained by reacting a hydrocarbyl polyoxyalkylene amine of the general formula 
wherein R1, R2, R3, R4, x, y and z have the aforestated meanings with a 1,2-epoxide of the general formula 
wherein R6 has the aforestated meaning.
Representatives of the hydrocarbyl polyoxyalkylene amine are known in the art, e.g., in U.S. Pat. No. 5,382,942, the contents of which are incorporated by reference herein. In general, the hydrocarbyl polyoxyalkylene amine can be prepared by first reacting an alkylaryl or hydrocarbyl alcohol represented by the general formula 
wherein R1 has the aforestated meaning with at least two 1,2-epoxides represented by the general formulae 
wherein R2 and R3 have the aforestated meanings. Optionally, a small amount of ethylene oxide, e.g., up to about 35 percent, can be added to the foregoing reaction to provide a hydrocarbyl polyoxyalkylene hydroxide represented by the general formula 
wherein R1, R2, R3, R4, x, y and z have the aforestated meanings. Preferred 1,2-epoxides for use herein include, but are not limited to, ethylene oxide, propylene oxide, butylene oxide and the like.
The hydrocarbyl alcohol and at least two 1,2-epoxides are advantageously reacted to form the hydrocarbyl polyoxyalkylene hydroxide in a mole ratio ordinarily ranging from about 5 to about 30 and preferably from about 10 to about 20. The reaction is ordinarily conducted at a temperature ranging from about 90xc2x0 C. to about 120xc2x0 C. and preferably from about 100xc2x0 C. to about 115xc2x0 C. The time for preparing the hydrocarbyl polyoxaylkylene hydroxide, under preferred parameters, will generally not exceed 8 hours.
The hydrocarbyl polyoxyalkylene hydroxide is then reacted with ammonia to provide the hydrocarbyl polyoxyalkylene amine. For example, the hydrocarbyl polyoxyalkylene hydroxide can be aminated by reacting the hydroxide with ammonia gas using well established animation methods. In general, the amount of ammonia reacted with the hydrocarbyl polyoxyalkylene hydroxide can range from about 1.0 cc/min to about 3.0 cc/min and preferably from about 1.5 cc/min Oto about 2.5 cc/min. The temperature of this reaction will ordinarily range from about 160xc2x0 C. to about 209xc2x0 C. and preferably from about 190xc2x0 C. to about 208xc2x0 C.
The hydrocarbyl polyoxyalkylene amine is then reacted with 1,2-epoxide or mixture thereof to form the desired hydrocarbyl polyoxyalkylene aminoalcohol utilized herein. Suitable 1,2-epoxides to react with the hydrocarbyl polyoxyalkylene amine include, but are not limited to, ethylene oxide, propylene oxide, butylene oxide, pentylene oxide, hexylene oxide and heptylene oxide. A preferred 1,2-epoxide for use herein is butylene oxide. Generally, the hydrocarbyl polyoxyalkylene amine and the 1,2-epoxide are advantageously reacted to provide a product mixture containing the product hydrocarbyl polyoxyalkylene aminoalcohol. During this condensation reaction, the predominate product formed in the product mixture is a mono-butoxylated amine. As one skilled in the art will readily appreciate, other products are unavoidably present in the product mixture during this reaction. For example, in addition to providing the predominate mono-butoxylated amine product, the product mixture may contain from about 0.1 weight percent up to about 25 weight percent apiece of (a) unreacted hydrocarbyl polyoxyalkylene amine and/or (b) a di-butoxylated amine.
In general, the 1,2-epoxide is reacted with the hydrocarbyl polyoxyalkylene amine in a mole ratio ranging from about 0.5:1 to about 50:1 and preferably from about 1:1 to about 7:1. An especially advantageous molar ratio is from about 1.0:1.1. The temperature for this reaction will ordinarily range from about 140xc2x0 C. to about 190xc2x0 C. and preferably from about I50xc2x0 C. to about.180xc2x0 C. The time period for this reaction will typically not exceed 8 hours.
The product hydrocarbyl polyoxyalkylene aminoalcohol can ordinarily be added prior to, simultaneously or after the lubricant component is added to the two-cycle engine fuel. It is also contemplated that the hydrocarbyl polyoxyalkylene aminoalcohol can be directly mixed with the lubricant component to form a two-cycle lubricant formulation and then adding the formulation to the two-cycle engine fuel.
In general, the two-cycle engine fuel combustion deposit-inhibiting amount of the hydrocarbyl polyoxalkylene aminoalcohol employed in the two-cycle engine fuel composition as a fuel additive can range from about 100 to about 2000 pounds per thousand barrels (PTB), preferably from about 500 to about 1100 PTB and more preferably from about 800 to about 1000 PTB.
In the fuel composition, other fuel additives can be employed with the additive of this invention, including, for example, antiknock agents such as tetraethyl lead compounds, anti-icing additives, antioxidants, metal deactivators, demulsifiers and the like.